Add imports macro

lib/runtime/examples/simple/main.rs

@@ -8,22 +8,17 @@ fn main() -> Result<()> {
     let wasm_binary = wat2wasm(IMPORT_MODULE.as_bytes()).expect("WAST not valid or malformed");
     let inner_module = runtime::compile(&wasm_binary, &CraneliftCompiler::new())?;
 
-    let mut env_namespace = Namespace::new();
-    env_namespace.insert(
-        "print_i32",
-        export_func!(
-            print_num,
-            [i32] -> [i32]
-        ),
-    );
+    let import_object = imports! {
+        "env" => {
+            "print_i32" => print_num<[i32] -> [i32]>,
+        },
+    };
 
-    let mut imports = ImportObject::new();
-    imports.register("env", env_namespace);
+    let inner_instance = inner_module.instantiate(import_object)?;
 
-    let inner_instance = inner_module.instantiate(imports)?;
-
-    let mut outer_imports = ImportObject::new();
-    outer_imports.register("env", inner_instance);
+    let outer_imports = imports! {
+        "env" => inner_instance,
+    };
 
     let outer_module = runtime::compile(EXAMPLE_WASM, &CraneliftCompiler::new())?;
     let mut outer_instance = outer_module.instantiate(outer_imports)?;

lib/runtime/src/lib.rs

@@ -32,7 +32,6 @@ pub use self::module::Module;
 use std::rc::Rc;
 
 pub mod prelude {
-    pub use crate::export_func;
     pub use crate::import::{ImportObject, Namespace};
     pub use crate::types::{
         FuncIndex, GlobalIndex, ImportedFuncIndex, ImportedGlobalIndex, ImportedMemoryIndex,
@@ -40,6 +39,7 @@ pub mod prelude {
         MemoryIndex, TableIndex, Type, Value,
     };
     pub use crate::vm;
+    pub use crate::{export_func, imports};
 }
 
 /// Compile a webassembly module using the provided compiler.

lib/runtime/src/macros.rs

@@ -50,3 +50,40 @@ macro_rules! __export_func_convert_type {
         compile_error!("Only `i32`, `u32`, `i64`, `u64`, `f32`, and `f64` are supported for argument and return types")
     };
 }
+
+#[macro_export]
+macro_rules! imports {
+    ( $( $ns_name:expr => $ns:tt, )* ) => {{
+        use wasmer_runtime::{
+            import::{ImportObject, Namespace},
+        };
+
+        let mut import_object = ImportObject::new();
+
+        $({
+            let ns = $crate::__imports_internal!($ns);
+
+            import_object.register($ns_name, ns);
+        })*
+
+        import_object
+    }};
+}
+
+#[macro_export]
+#[doc(hidden)]
+macro_rules! __imports_internal {
+    ( { $( $imp_name:expr => $func:ident < [ $( $params:ident ),* ] -> [ $( $returns:ident ),* ] >, )* } ) => {{
+        let mut ns = Namespace::new();
+        $(
+            ns.insert($imp_name, $crate::export_func!(
+                $func,
+                [ $( $params ),* ] -> [ $( $returns )* ]
+            ));
+        )*
+        ns
+    }};
+    ($ns:ident) => {
+        $ns
+    };
+}